If you really are serious about elk and can in FACT shoot a 12GA w/ no problems, I would go with a 7rem mag, 30-06, or 300win mag. Anything smaller your getting iffy for elk, not that you cant kill elk w/ smaller calibers, but your in the same boat w/ elk that your in w/ the 223 for deer.... That being...perfect shot-dead deer: marginal shot-??????